[peteeng]

Hi Galeb - The main issue with thread rivets is that you will not be able to pull up to the surface due to the rivet flange. if you are concerned about thread depth use a thicker tube. Doesn't hurt extra stiffness... forget about fillers just use thicker tube... Peter

[joeavaerage]

Hi,
I agree with Peteng, make the wall of the tube at least 6mm, or thicker if you can find it, then you can just drill and tap.

Damping is when a material is flexing and it dissipates motional energy as heat. If you fill the tubes with concrete or something similar the adhesion between the filler and the tube
will be the only mechanical transfer of motional (flex) energy to the filler, and a proportion of it will dissipate as heat. The whole point of using steel is that it is stiff so it will flex very little,
hopefully a few um at most, and so that few um of flex is the MOST amount of flexure of the filler as well. How much energy would you expect concrete to dissipate if you only flex it a few um?

Don't worry about damping....its nice to have but unless a machine is stiff its a pile on junk that wont be used. Make the hollow sections as thick a wall as you can possibly find. Even consider making them out
of solid steel or getting them laser cut out of 50mm or 60mm plate. Around here it works out to about $6.00 NZD ($4.00USD) per kg for 50mm medium tensile plate laser cut (to simple shapes at least).

Craig

[CLEFAVOUR]

Peter, Craig, Thank you for your responses. I'm sure that a thicker frame will be more ideal for this situation, but that may have to be a "down the road" upgrade.
I currently have this existing frame, so I am trying to utilize as much as I can to at least have a functional machine with the materials that I have.
As for the flange of the threaded rivets, I was planning to just add clearance so that the part could butt-up directly to the frame surface.
The Z assembly would have 4 x 5/16-18 SHCS for mounting and 2 x 1/4-28 SCHS for tramming on three sides of the mount (x-, x+ and y+).

In a perfect world, I would just just commission someone to build a whole new frame( which may still happen at some point), but for now, I would just like to know how I can use what I have.

If you honestly think that it silly to even try with what I have, then this build is going to take much longer than expected as my pockets aren't very deep and it may take some time for me to get someone to rebuild this with thicker steel.

[peteeng]

Hi Caleb - It appears you have access to the back of this area via the hole in the member. So make threaded backing plates and epoxy them in place. I'd prefer a backing plate to a thread insert. or soft solder nuts in the back...Peter

[CLEFAVOUR]

Hi Peter,
That's a great idea that I haven't even given thought to! thanks for the tip.
I've been skeptical about the rivet idea, just in the fact that they may end up becoming loose at some point and I would lose my mounting threads. But, a backup plate would be perfect and simple to make.

I've sent my father some dimensions of the current frame, and I'm waiting for his company to give me a quote to have it rebuilt out of 3/8" thick steel for some more rigidity.
Hopefully its reasonably priced. I'd be much more comfortable with thicker walls to tap into.